The magistrate who granted Man Haron Monis bail two months before the Sydney siege was never told the gunman had allegedly committed sexual assault while on bail for an earlier offence, a coroner’s inquest has heard.

Had that information been raised with the court, “it’s at least possible that Mr Monis’s bail may have been refused”, counsel assisting Jeremy Gormly SC said.

The second phase of the coronial inquest into the December 2014 siege at the Lindt cafe in Martin Place commenced in Sydney on Monday.

It will examine whether Monis should have been granted bail, the origins of his gun, his relations with Australia’s Muslim communities and whether his actions could be considered terrorism.

A panel of experts, including barrister Ian Temby QC, has reviewed Monis’s three successful bail applications between 2009 and 2014, finding the latest “could have been handled differently”, Gormly said.

Monis was found to meet the bail criteria – which have since been amended – because the “unacceptable risk” he posed could be mitigated by conditions.

But the prosecutor in the case was never told that Monis had been accused of three counts of sexual assault while on bail for earlier offences in 2010.

“It’s the view of the expert bail panel that, had a detention application been made that drew the court’s attention to these various considerations, it’s at least possible that Mr Monis’s bail may have been refused,” Gormly said.

The bungle raised issues around the lack of information-sharing between states and federal agencies. “It may be that what happened here is the price we pay for having eight jurisdictions instead of one,” he said.

Detective senior constable Denise Vavayis from the NSW police sex crimes squad who headed the investigation that had Monis charged with 43 sexual and indecent assaults said she had always opposed Monis’ bail.

Vavayis did not know Monis was on bail at the time of three of the alleged offences and defended not investigating the avenue.

“My primary focus in my job is to present to the DPP what our concerns are in relation to bail,” she said.

“Our primary focus was on the fears they [the victims] held and my primary focus was on his behaviour and propensity to violence, it was not on the minute detail of the charges that had gone before.”

Vavayis said it would have been quite a complex task to find out about Monis’s previous bail as the offences were under commonwealth laws, not NSW ones.

Police opposed the bail of Monis when he was charged with the initial sexual and indecent assaults but did not appeal against the decision after the DPP’s advice was that a review was unlikely to be successful.

In October 2014 when Monis was charged with a further 40 offences, police did not oppose bail after advice from the DPP that it was also unlikely to be successful.

The inquest was also told the DPP solicitor who handled the bail application had not done a bail application in NSW before and had started working for the DPP two months before.

Where Monis had sourced the crudely sawn-off shotgun he wielded during the siege was still a mystery, Gormly said.

The US-imported weapon was likely to have come from the enormous “grey market” of weapons that were never registered or handed to the federal government after the 1996 gun buyback, thought to number about 250,000 firearms.

Gormly said it was likely the gun had been acquired recently, because it had not been discovered during the most recent search of Monis’s home in 2013.

The question of whether the siege was an act of terrorism had split a panel of experts commissioned by the coroner.

The Lowy Institute’s Rodger Shanahan pointed to the lack of contact between the gunman and Islamic State agents to argue Monis was “someone with mental health issues acting on his own personal grudges”, rather than any ideological agenda.

But Bruce Hoffman, from Georgetown University, argued otherwise, pointing to Monis’s apparent inspiration by Isis, his demand to speak to the prime minister and strategic choice of a location near the Channel Seven studios.

A psychologist, Kate Burrell, had also advised the coroner on whether Monis could have been considered to be “radicalised” at the time of the siege.

She found his actions were “in part the result of some radicalisation towards violent extremism”, according to junior counsel assisting, Sophie Callan, but the siege was “more an act of desperation than radicalisation”.

“For a man like Mr Monis, with all his mental health problems, the availability of global jihadist and Isis rhetoric provides a powerful outlet,” Callan said.

The inquest will also hear further details of Monis’s life in Iran before his emigration to Australia in 1996. It will continue for two weeks.